Method and Device for the Production of Metal Slurry, and Method and Device for Produciton of Ingot

ABSTRACT

With a device including a melting furnace ( 11 ) for melting metals to form a molten metal (M), a tilted cooling body ( 31 ) allowing the molten metal (M) delivered from the melting furnace ( 11 ) to be poured thereon from above, and a tilted cooling body vibrating mechanism ( 36 ) for imparting vibration to the tilted cooling body ( 31 ), this invention can produce metal slurry possessing fine spherical crystals efficiently and continuously.

TECHNICAL FIELD

This invention relates to a method and a device for the production ofmetal slurry in a partly molten (partly solidified) state allowing thecoexistence of a metal in a molten state (liquid phase) and a metal in asolidified state (solid phase), and a method and a device for theproduction of an ingot from the partly molten (partly solidified) metalslurry.

BACKGROUND ART

Generally, as casting methods which utilize rheology and thixotropy of apartly molten and partly solidified metal, namely the quality of lowviscosity and excellent fluidity, the rheocast method (partly solidifiedcasting method) resorting to the former property and the thixocastingmethod (partly molten casting method) resorting to the latter propertyhave been known.

These casting methods invariably perform casting by using metal slurryin a partly molten and partly solidified state allowing the coexistenceof a molten liquid-phase metal and a solid-phase metal.

The cast structures of the ingot produced by the casting methodsdescribed above, the cast magnesium alloy and other various metals andalloys are preferred to be wholly in the form of very small spheresbecause they are required to avoid revealing directionality of crystal,excel in various mechanical properties and suppress segregation ofcomponents.

With the object of grain-refining and spheroidizing the cast structure,a molten metal, for example, is poured onto a tilted cooling body andcooled by this tilted cooling body or the molten metal is added with agrain refining agent and subjected to electromagnetic stirring ormechanical stirring (refer, for example, to JP-A 2001-252759 and JP-AHEI10-128516).

When the molten metal is poured onto the tilted cooling body andconsequently cooled by the tilted cooling body, however, since thismolten metal is suddenly cooled on the surface of the tilted coolingbody, the solidification of the resultant metal slurry often occurs onthe tilted cooling body, with the possible result that the metal slurrywill be prevented from being produced continuously.

Particularly, when the molten metal is formed of a magnesium alloy, itencounters difficulty in continuously producing metal slurry under theexisting circumstances because the magnesium alloy readily solidifiesowing to its small latent heat of solidification.

When the molten metal is enabled by the addition of a grain refiningagent to give rise to crystals in the form of very small spheres, thisprocedure is not applicable to all the metals but is applicable toaluminum alloys and magnesium alloys exclusively and it further requiresthe amount of the grain refining agent to be added and the temperatureof addition to be exactly controlled and moreover imposes a limit on thetime of retention of the grain-refined state of crystals subsequent tothe addition of the grain refining agent.

When the molten metal is subjected to an electromagnetic stirring or amechanical stirring, this procedure entails an addition to the deviceand an increase in the cost of energy.

This invention, therefore, is aimed at providing a method and a devicefor the production of metal slurry ideally and continuously by using atilted cooling body.

This invention is also aimed at providing a method and a device for theproduction of metal slurry ideally and continuously even when the moltenmetal is formed of a magnesium alloy.

This invention is further aimed at providing a method and a device forthe production of metal slurry at a suppressed energy cost withoutenlarging the device as compared with a device of mechanical stirring ora device of electric stirring.

DISCLOSURE OF THE INVENTION

This invention provides a method for the production of metal slurry,comprising pouring a molten metal onto a tilted cooling body andallowing the molten metal to cool on the tilted cooling body, whereinvibration is imparted to the tilted cooling body.

This invention further provides a method for the production of metalslurry, comprising pouring a molten metal onto a vibrating cooling bodyand causing the vibrating cooling body to cool the molten metal.

In each of the methods for the production of metal slurry, the moltenmetal is formed of a magnesium alloy.

This invention also provides a device for the production of metalslurry, comprising a tilted cooling body onto which a molten metal ispoured and which is equipped with a tilted cooling body vibratingmechanism for imparting vibration to the tilted cooling body.

This invention further provides a device for the production of metalslurry, comprising a cooling body onto which a molten metal is poured tocool the molten metal and which is equipped with a cooling bodyvibrating mechanism for imparting vibration to the cooling body.

In each of the devices for the production of metal slurry, the moltenmetal is formed of a magnesium alloy.

This invention also provides a method for the production of an ingot,comprising supplying a mold with a molten metal and cooling the moltenmetal by cooling the mold, wherein vibration is imparted to the mold.

This invention also provides a method for the production of an ingot,comprising pouring a molten metal onto a vibrating cooling body to coolthe molten metal with the vibrating cooling body, supplying the cooledmolten metal to a mold and further cooling the cooled molten metal bycooling the mold.

In each of the methods for the production of an ingot, the molten metalis formed of a magnesium alloy.

This invention also provides a device for the production of an ingot,comprising a mold to which a molten metal is supplied and which iscooled and equipped with a mold vibrating mechanism for impartingvibration to the mold.

This invention further provides a device for the production of an ingot,comprising a cooling body onto which a molten metal is poured forcooling the molten metal, a mold to which the cooled molten metal issupplied and which is cooled to further cool the cooled molten metal anda cooling body vibrating mechanism for imparting vibration to thecooling body.

In each of the devices for the production of an ingot, the molten metalis formed of a magnesium alloy.

According to the method and the device for the production of a metalslurry contemplated by this invention, since a tilted cooling bodyvibrating mechanism is provided for the purpose of preventing a moltenmetal from being solidified on a tilted cooling body or the tiltedcooling body vibrating mechanism is provided for the purpose of causingcrystals forming on a surface of the tilted cooling body to be forciblyliberated and flowed down during an initial stage of formation ofcrystals or preventing the molten metal from being solidified on thecooling body in order that the crystals forming on the surface of thecooling body may be forcibly liberated and flowed down during theinitial state of the formation of the crystals, the metal slurrypossessing crystals of a form of very small spheres can be efficientlyand continuously produced without enlarging the device as compared withthe device of mechanical stirring or electromagnetic stirring or withoutincreasing a cost of energy, and the produced metal slurry can beenabled to possess crystals of the form of smaller spheres than themetal slurry obtained by the conventional procedure which contemplatesno impartation of vibration to the tilted cooling body.

Since the molten metal is formed of a magnesium alloy, when the metalslurry is cast in its original form of globular crystals, the time forfinishing the produced casting can be shortened and the number ofcasting steps can be decreased.

According to the method and the device for the production of an ingotcontemplated by this invention, since a mold vibrating mechanism isprovided for the purpose of preventing a molten metal from adhering toand solidified in the mold and causing crystals forming on the innersurface of the mold to be forcibly liberated during the initial stage ofthe formation of the crystals or a cooling body vibrating mechanism isprovided for the purpose of preventing the molten metal from adhering toand solidified on the cooling body and causing crystals forming on thesurface of the cooling body to be forcibly liberated and flowed downduring the initial stage of the formation of the crystals, the caststructure of a varying kind of metal can be reduced to wholly smallerspheres than the cast structure obtained by the conventional procedurewhich contemplates no impartation of vibration to the mold withoutenlarging the device as compared with the device for mechanical stirringor electromagnetic stirring or increasing the cost of energy.

Even from a magnesium alloy which possesses a particularly small latentheat of solidification and therefore readily solidifies and rendersdifficult the production of metal slurry in a partly molten state, thisinvention can easily produce manganese alloy slurry.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram schematically illustrating theconstruction of a device for continuous production of a cast bar by theapplication of the first embodiment of the device for the production ofmetal slurry according to this invention.

FIG. 2 is a copy of an optical micrograph illustrating the solidifiedstructure resulting from reheating and solidifying a continuous cast barproduced by the conventional device for the production of a continuouscast bar.

FIG. 3 is a copy of an optical micrograph illustrating the solidifiedstructure resulting from reheating and solidifying a continuous cast barproduced by the device for the production of a continuous cast bar shownin FIG. 1.

FIG. 4 is a cross section schematically illustrating the construction ofthe second embodiment of the device for the production of an ingotcontemplated by this invention.

FIG. 5 is a plan view schematically illustrating the construction of amold conveying mechanism for the device for the production of the ingotshown in FIG. 4.

FIG. 6 is a copy of an optical micrograph illustrating the solidifiedstructure resulting from reheating and solidifying an ingot produced bythe conventional device for the production of an ingot.

FIG. 7 is a copy of an optical micrograph illustrating the solidifiedstructure resulting from reheating and solidifying an ingot produced bythe device for the production of an ingot according to the secondembodiment of this invention.

FIG. 8 is a partial cross section schematically illustrating theconstruction of the third embodiment of the device for the production ofan ingot contemplated by this invention.

FIG. 9 is a cross section schematically illustrating the construction ofanother example of the melting furnace to be used in the device for theproduction of a continuous cast bar or the device for the production ofan ingot.

BEST MODE FOR CARRYING OUT THE INVENTION

This invention will be described more specifically below with referenceto the accompanying drawings.

Referring to FIG. 1, an device I for the production of a continuous castbar comprises a melting furnace 11 for melting metals and producing amolten magnesium alloy (molten metal M), a melting furnace temperatureadjusting mechanism 17 for adjusting the melting furnace 11 to arequired melting temperature, a molten metal discharge controllingmechanism 21 for controlling the amount of the molten metal M to bedischarged from the melting furnace 11, a tilted cooling body 31 forcooling the molten metal M discharged from the melting furnace 11 andpoured to the upper part thereof till metal slurry U in a partly moltenstate, a tilted cooling body vibrating mechanism 36 for impartingvibration to the tilted cooling body 31, a cylindrical mold 41 suppliedwith the metal slurry from the tilted cooling body 31, a mold coolingmechanism 51 for cooling the mold 41, a refrigerant cooling mechanism 61for cooling a refrigerant 53 for the mold cooling mechanism 51, a feedroller mechanism 71 for drawing a continuous cast bar B from the mold 41at a required casting speed, and a cutting mechanism 81 for cutting thecontinuous cast bar B fed out by the feed roller mechanism 71 intobillets L of a prescribed length.

Incidentally, a device S for the production of metal slurry comprisesthe melting furnace 11 through the tilted cooling body vibratingmechanism 36.

The melting furnace 11 comprises a main body 12 of the melting furnaceopened in the upper end, a delivery tube 13 fitted in an airtight mannerthrough the bottom of the main body 12 and so disposed as to have theupper terminal thereof fall at a prescribed position inside the mainbody 12, a heater 14 embedded in the main body 12, and a lid 15 forblocking the upper part of the main body 12.

Then, the main body 12 of the melting furnace is provided on the bottomthereof with a dross vent 16 for release of a sedimented impurity, suchas dross.

The melting furnace temperature adjusting mechanism 17 comprises athermocouple 18 as an instrument for measuring the temperature in themelting furnace 11 and an electrification controlling part 19 forstarting supply of electric power to the heater 14 to enable thetemperature detected by the thermocouple 18 to reach the preset meltingtemperature and stopping the supply of the electric power to the heater14.

Incidentally, the temperature in the melting furnace 11 is set by themelting furnace temperature adjusting mechanism 17 at a level not lowerthan the liquid phase temperature of the magnesium alloy so as toproduce the molten metal M of the magnesium alloy.

The molten metal delivery controlling mechanism 21 comprises aheater-embedded control bar 22 inserted through an insertion hole 15 aformed in the lid 15 of the melting furnace 11 and a control bar drivingpart 23 for inserting the heater-embedded control bar 22 into themelting furnace 11 and delivering the molten metal M from the deliverytube 13.

The tilted cooling body 31 is installed at an elevation angle in therange of 20 degrees to 80 degrees and is set at a constant temperatureby a water-cooled or air-cooled tilted cooling body cooling mechanismwhich is omitted from illustration herein.

The molten metal M flowing down on the tilted cooling body 31,therefore, has the temperature thereof lowered during the course of theflow.

That is, the temperature of the magnesium alloy on the tilted coolingbody 31 falls at a level not higher than the liquidus temperature of amagnesium alloy and not lower than the solidus temperature of themagnesium alloy.

The reason for setting the temperature of the molten magnesium alloyflowing down on the tilted cooling body 31 below the liquidustemperature of the magnesium alloy and above the solidus temperature ofthe magnesium alloy is that the spheroidal crystals formed when themolten metal M is cooled are enabled to retain the form of slurry in apartly molten state without being dissolved, dissipated or completelysolidified.

The tilted cooling body vibrating mechanism 36 comprises an eccentricshaft and a motor, for example, and is intended to impart vibration tothe tilted cooling body 3 in order that the solidified shell of themolten metal M adhering to the tilted cooling body 31 may be forciblyliberated during the initial stage of the formation thereof

The mold 41 comprises a main body 42 of the mold in the shape of acylinder opened at both the terminals and a flange part 43 disposed onthe outer periphery of one (upper) terminal of the main body 42 of themold.

Then, the mold 41 is retained by a mold retaining unit 46 which, in astate transfixed with the main body 42 of the mold, allows the flangepart 43 to engage the upper terminal thereof.

The mold cooling mechanism 51 comprises a cooling bath 52 having thebottom thereof transfixed with the main body 42 of the mold 41 in awatertight manner and a refrigerant 53 contained in the cooling bath 52.

The refrigerant cooling mechanism 61 comprises a piping 62 having boththe terminals thereof connected to the cooling bath 52, a refrigerantcooling part 63 disposed halfway along the length of the piping 62, anda pump 64 disposed halfway along the length of the piping 62 and adaptedto circulate the refrigerant 53 in the cooling bath 52.

Incidentally, the refrigerant 53 is set by the refrigerant coolingmechanism 62 at a constant temperature for solidifying the metal slurryU in the partly molten state such as, for example, at a level of nothigher than the solidus temperature of the magnesium alloy.

The feed roller mechanism 71 comprises a pair of rollers 72 for nippingand drawing the continuous cast bar B emanating from the mold 41 and arotary drive part (73) not shown that is adapted to rotate at least oneof the pair of rollers 72 at an expected casting speed.

The cutting mechanism 81 comprises a cutting blade 82 for cutting thecontinuous cast bar B delivered by the feed roller mechanism 71 intobillets L of a prescribed length, a motor 83 for rotating the cuttingblade 82, and a mobile driving part (84) not shown that is adapted tomove the motor 83 in the horizontal direction.

The production of the continuous cast bar B and the billet L will bedescribed below.

After the main body 12 of the melting furnace has been charged withnecessary metals and then closed with the lid 15, the molten metal M ofmagnesium alloy is formed by heating the main body 12 of the meltingfurnace with the heater 14, thereby melting the metals.

Then, by driving the heater-embedded control bar 22 downwardly with thecontrol bar driving part 23, the molten metal M is successivelydelivered from the delivery tube 13 onto the tilted cooling body 31.

Since the magnesium alloy has the smallest specific gravity in all thepractical metals when the molten metal M is delivered in this manner,most impurities and compounds sediment to the bottom of the main body 12of the melting furnace. By extracting the supernatant of the moltenmetal M, therefore, it is made possible to supply the molten metal Mdeprived of substantially all the impurities and compounds to the upperpart of the tilted cooling body 31.

The impurities which sediment to the bottom of the main body 12 of themelting furnace are called “dross.” Inclusion of this dross prevents theproduced magnesium alloy from becoming clean and suffers it to become arejected product. Thus, the amount of the molten metal M that can beexpelled by lowering the heater-embedded control bar 22 is preferred tobe 70% to 80% of the interior volume of the main body 12 of the meltingfurnace from the side lower than the upper end of the delivery tube 13.

The dross which has sedimented to the bottom of the main body 12 of themelting furnace is only required to be expelled by properly manipulatingthe dross vent 16.

The molten metal M delivered onto the tilted cooling body 31 asdescribed above is cooled by contact with the surface of the tiltedcooling body 31 and consequently crystallized partly and converted intothe partly melted and partly solidified metal slurry U and eventuallysupplied as such to the mold 41.

Since the tilted cooling body 31 is being vibrated at this time by thetilted cooling body vibrating mechanism 36, the solidified shell, ifsuffered to adhere to the tilted cooling body 31, is forcibly liberatedin the form of small spheres during the initial stage of the formationthereof and consequently spheroidized.

The metal slurry U which has been supplied into the mold 1 is cooledwith the mold cooling mechanism 51 and is then cast into the continuouscast bar B by the use of a dummy bar.

The continuous cast bar B produced in this manner is conveyed by thefeed roller mechanism 71 and cut by the cutting mechanism 81 intobillets L of a prescribed length.

These billets L are used as in forging or extrusion or, as occasiondemands, are heated by a partly melting work till they acquire a partlymolten state.

The solidified structure observed under an optical microscope of abillet which was produced by a continuous cast bar producing devicedevoid of a tilted cooling body vibrating mechanism and subsequentlyreheated and solidified is illustrated in FIG. 2 and the solidifiedstructure observed under an optical microscope of a billet which wasproduced by the continuous cast bar producing device I of the firstembodiment of this invention and subsequently reheated and solidified isillustrated in FIG. 3.

The solidified structure of the billet produced by the continuous castbar producing device devoid of the tilted cooling body vibratingmechanism, as seen from FIG. 2, was formed of spheroidized crystalsgrown to a size of no less than several hundreds of μm.

The solidified structure of the billet produced by the continuous castbar producing device 1 of the first embodiment of this invention, asseen from FIG. 3, was formed of fine spherical crystals measuring 10 μmto 200 μm in diameter.

According to the metal slurry producing device S of the first embodimentof this invention, since the tilted cooling body vibrating mechanism 36is provided for the purpose of preventing the molten metal M from beingsolidified on the tilted cooling body 31 and since the crystals formedon the surface of the tilted cooling body 31 are forcibly liberated andflowed down during the initial state of their formation as describedabove, the metal slurry U comprising fine spherical crystals such as,for example, spherical crystals measuring 10 μm to 200 μm can beefficiently and continuously produced without enlarging the device inuse as compared with the device of mechanical stirring orelectromagnetic stirring or without adding to the cost of energy, andthe metal slurry U comprising finer spherical crystals can be obtainedthan by the conventional procedure avoiding impartation of vibration tothe tilted cooling body.

Since the molten metal M is formed of a magnesium alloy, the billets Lcomprising fine spherical crystals can be produced. When the billets Lare forged or cast in a partly molten state, the finishing time can beshortened and the number of steps of the finishing work can bedecreased. When the metal slurry U is cast in the original form ofspherical crystals, the time for finishing the casting can be shortenedand the number of steps of the finishing work can be decreased.

FIG. 4 is an explanatory diagram equivalent to a side sectionillustrating the schematic structure of an ingot producing device of thesecond embodiment of this invention and FIG. 5 is an explanatory diagramequivalent to a plan view illustrating the schematic structure of themold conveying mechanism in the ingot producing device of the secondembodiment of this invention.

Incidentally, FIG. 4 is equivalent to a cross section taken through FIG.5 along line A-A.

In FIG. 4 or FIG. 5, an ingot producing device P comprises a meltingfurnace 111 for melting metals and forming a molten magnesium alloy(molten metal M), a melting furnace temperature adjusting mechanism 117for adjusting the melting furnace 111 to a necessary meltingtemperature, a molten metal delivery controlling mechanism 121 forcontrolling the amount of the molten metal M delivered from the meltingfurnace 111, a mold 131 to which the molten metal M from the meltingfurnace 111 is supplied, a mold conveying mechanism 141 for conveyingthe mold 131, a mold cooling mechanism 151 for cooling the mold 131conveyed by the mold conveying mechanism 141, a mold cooling refrigerantcooling mechanism 161 for cooling a refrigerant 153 for the mold coolingmechanism 151, and a mold vibrating mechanism 171 for impartingvibration to the mold 131 conveyed by the mold conveying mechanism 141from the melting furnace 111 to the position Pa for supply of the moltenmetal M (position of vibration).

The melting furnace 111 comprises a main body 112 of the melting furnaceopened in the upper part, a delivery tube 113 mounted in a watertightmanner as transfixed to the bottom of the main body 112 of the meltingfurnace and having the upper terminal thereof set at the prescribedposition inside the main body 112 of the melting furnace, a heater 114embedded in the main body 112 of the melting furnace, and a lid 115 forblocking the upper part of the main body 112 of the melting furnace.

Then, the main body 112 of the melting furnace is provided on the bottomthereof with a dross vent 116 for withdrawing dross, for example.

The melting furnace temperature controlling mechanism 117 comprises athermocouple 118 as a temperature measuring unit for measuring thetemperature in the melting furnace 111 and an electrificationcontrolling part 119 for starting supply of electric power to the heater114 so as to enable the temperature detected by the thermocouple 118 toreach the present melting temperature or stopping the supply of theelectric power to the heater 114.

The temperature in the melting furnace 111 is set by the melting furnacetemperature adjusting mechanism 117 at the level of not lower than theliquidus temperature of the magnesium alloy for the purpose of formingthe molten metal M of the magnesium alloy.

The molten metal delivery controlling mechanism 121 comprises aheater-embedded control bar 122 inserted into an insertion hole 115 aformed in the lid 115 of the melting furnace 111 and a control bardriving part 123 for inserting the heater-embedded control bar 122 intothe melting furnace 111 and consequently expelling the molten metal Mfrom the delivery tube 113.

The mold 131 comprises a cylindrical main body 132 of the mold opened atone terminal (upper terminal) and a flange part 133 disposed on theouter periphery of the one terminal (upper terminal) of the main body132 of the mold.

The mold conveying mechanism 141 comprises a mold retaining part 142which, in a state transfixed with the main body 132 of the mold, enablesthe flange part 133 to be detachably fixed at the upper terminalthereof, a conveyor 143 for conveying a plurality, eight in the presentexample, of mold retaining parts 142 as spaced in an elliptical course,a driving toothed wheel 144 and a driven toothed wheel 145 forforwarding the conveyor 143 in an elliptical course, and a conveyancedriving part (146) not shown that is adapted to repeat an operation ofdriving the driving toothed wheel 144 over a prescribed distanceclockwise in the bearings of FIG. 5, for example, and stop it for aprescribed duration.

Incidentally, in FIG. 5, Ps denotes a mold mounting position formounting the mold 131 to the mold retaining part 142 which is forwardedby the conveyor 143, Pa denotes a molten metal supplying position forsupplying the molten metal M from the melting furnace 111 to the mold131 advanced on the conveyor 143 or a vibrating position for impartingvibration with the mold vibrating mechanism 171 to the mold 131 advancedon the conveyor 143, and Po denotes a mold demounting position fordemounting the mold 131 from the mold retaining part 142 forwarded onthe conveyor 143.

The mold cooling mechanism 151 comprises a cooling bath 152 throughwhich the mold 131 conveyed by the mold conveying mechanism 141 passesand the refrigerant 153 contained in this cooling bath 152.

The cooling bath 152 is elliptically formed as illustrated in FIG. 5 andenabled to contain the refrigerant 153 between the partition wall 152 aformed at the upstream position from the mold mounting position Ps andthe partition wall 152 b formed at the downstream position from the molddemounting position Po.

The mold cooling refrigerant cooling mechanism 161 comprises a piping162 having the opposite terminals thereof connected to the cooling bath152, a refrigerant cooling part 163 disposed halfway along the length ofthe piping 162, and a pump 164 disposed halfway along the length of thepiping 162 and adapted to circulating the refrigerant 153 inside thecooling bath 152.

Incidentally, the refrigerant 153 is set by the mold cooling refrigerantcooling mechanism 161 at a constant temperature for solidifying themolten metal M such as, for example, the level not higher than thesolidus temperature of the magnesium alloy.

The reason for setting the temperature of the refrigerant 153 at a levelof not higher than the solidus temperature of the magnesium alloy isthat the crystals formed on the inner surface of the main body 132 ofthe mold are enabled to be liberated by the vibration of the main body132 of the mold and consequently transformed into a partly solidifiedstate or to a solidified state.

The mold vibrating mechanism 171 comprises a transmitting member 172provided with a notch 172 a for holding the flange part 133 of the mold131, a vibrating part 173 mounted on the right side upper surface of thetransmitting member 172 and comprising an eccentric shaft and a motor,for example, and a transmitting member moving drive part (174) not shownthat is adapted to allow movement of the transmitting member 172 betweenthe retired position (the position indicated with a solid line in FIG. 4and FIG. 5) in which the mold 131 can be conveyed by the mold conveyingmechanism 141 without requiring the flange part 133 to be held in thenotch 172 a and the advanced position (the position indicated with atwo-dot chain line in FIG. 4 and FIG. 5) at which the flange part 133 isheld in the notch 172 a.

Now, the production of the ingot N will be described below.

First, the molten metal M of a magnesium alloy is formed by charging themain body 112 of the melting furnace in the state illustrated in FIG. 4with necessary metals, closing the main body 112 of the melting furnacewith the lid 115, and heating the main body 112 of the melting furnacewith the heater 114, thereby melting the metals.

By actuating the mold conveying mechanism 141, the conveyor 143 is movedand the molds 131 are retained by the mold retaining parts 142successively conveyed to the mold mounting position Ps, and the mainbodies 132 of the molds are partly embedded in the refrigerant 153 ofthe cooling bath 152.

When the mold 131 mounted on the mold retaining part 142 as describedabove and advanced by the conveyor 143 to the molten metal supplyingposition (vibrating position) Pa and brought to a stop at that position,the transmitting member moving drive part (174) not shown advances thetransmitting member 172 and causes the flange part 133 of the mold 131to be contained in the notch 172 a and the vibrating part 173 isactuated as well to impart vibration to the mold 131.

Then, by driving and descending the heater-embedded control bar 122 withthe control bar driving part 123, the molten metal M is enabled to bedelivered in a prescribed amount from the delivery tube 113 into themold 131.

When the molten metal M is delivered in this manner, the amount of themolten metal M that can be delivered by lowering the heater-embeddedcontrol bar 122 is preferred to be in the range of 70% to 80% of thevolume of the main body 112 of the melting furnace below the upperterminal of the delivery tube 113 in order that the magnesium alloyclean by not including dross may be delivered.

Then, the dross which has sedimented to the bottom of the main body 112of the melting furnace may be discharged by properly manipulating thedross vent 116.

The molten metal M delivered in the prescribed amount into the main body132 of the mold as described above is cooled by contacting the innersurface of the main body 132 of the mold and consequently crystallizedand spheroidized and caused to adhere to the inner surface of the mainbody 132 of the mold.

Since the mold 131 is vibrated by the mold vibrating mechanism 171, thespherical crystals are grown and forcibly liberated from the innersurface of the main body 132 of the mold and successively sedimented tothe bottom of the main body 132 of the mold and turned into the ingot N.

When the mold 131 placed at the molten metal delivering position(vibrating position) Pa has been vibrated for a prescribed duration suchas, for example, in the approximate range of 1 minute to 5 minutes, thevibrating part 173 is stopped and the transmitting member 172 isretracted with the transmitting member moving driving part (174) notshown.

Then, the mold conveying mechanism 141 repeats an operation of conveyingthe mold 131 supplied with the molten metal M to a prescribed distancetoward the mold demounting position Po, conveying the next mold 131 tothe molten metal supplying position (vibrating position) Pa, andsupplying the molten metal M from the melting furnace 111 as keptvibrated as described above to the mold 131 conveyed to the molten metalsupplying position (vibrating position) Pa.

Since the mold 131 which has been conveyed to the mold demountingposition Po has the metal slurry U initially held in a partly solidifiedstate already solidified into the ingot N, it is removed from the moldretaining part 142, reversed to expel the ingot N, and given a cleaningof the interior thereof in preparation for next use.

The solidified structure observed under an optical microscope of aningot produced by the ingot producing device devoid of a mold vibratingmechanism and reheated and solidified is shown in FIG. 6 and thesolidified structure observed under an optical microscope of an ingot Nproduced by the ingot producing deice P of the second embodiment of thisinvention and reheated and solidified is illustrated in FIG. 7.

The solidified structure of the ingot produced by the ingot producingdevice devoice of a mold vibrating mechanism, as noted from FIG. 6, hascrystals grown to a size exceeding several hundreds of μm.

However, the solidified structure of the ingot N produced by the ingotproducing device P of the second embodiment of this invention, as notedfrom FIG. 7, has fine spherical crystals in the range of 10 μm to 200μm.

According to the ingot producing device P of the second embodiment ofthis invention, since the mold vibrating mechanism 171 is provided forthe purpose of preventing the molten metal M from solidifying asadhering to the mold 131 and the crystals formed on the inner surface ofthe mold 13′ is forcibly liberated during the initial state of formationthereof, the cast structure of a varying kind of metal can be formed inwholly finer spheres measuring 10 μm to 200 μm, for example, than theconventional procedure avoiding imparting vibration to the mold withoutenlarging the device in use as compared with the device of mechanicalstirring or the device of electromagnetic stirring or without increasingthe cost of energy.

Since the molten metal M is formed of a magnesium alloy, it is enabledto shorten the time for finishing the ingot N and decrease the number ofsteps of the finishing process.

FIG. 8 is an explanatory diagram equivalent to a partial lateral sectionillustrating schematically the structure of the ingot producing deviceas the third embodiment of this invention and the parts identical orequivalent to those found in FIG. 4 and FIG. 5 are denoted by the likereference numerals and will be omitted from the description.

Referring to FIG. 8, the ingot producing device P comprises a meltingfurnace (111) for melting metals and forming a molten metal M of amagnesium alloy, a melting furnace temperature adjusting mechanism (117)for adjusting the melting furnace (111) to a necessary meltingtemperature, a molten metal delivery controlling mechanism (121) forcontrolling the amount of the molten metal M delivered from the meltingfurnace (111), a mold 131 for receiving the molten metal M supplied fromthe melting furnace (111), a mold conveying mechanism 141 for conveyingthe mold 131, a mold cooling mechanism (151) for cooling the mold 131conveyed by the mold conveying mechanism 141, a mold cooling refrigerantcooling mechanism (161) for cooling the refrigerant (153) for the moldcooling mechanism (151), a cooling body 211 of a hemispheric shape, forexample, inserted into the mold 131 placed at the molten metal supplyingposition (vibrating position) (Pa) and adapted to admit the pour thereinof the molten metal M, a cooling body vibrating mechanism 221 forimparting vibration to the cooling body 211, and a cooling body coolingmechanism 231 for cooling the cooling body 211.

The melting furnace (111) to the mold cooling refrigerant coolingmechanism (161), though omitted from illustration, are constructed inthe same manner as in the second embodiment.

The cooling body vibrating mechanism 221 comprises two pipes 222 bentlike a crank, closed at one terminal (right terminal), fixed at theother terminal, enabled the other terminal (left terminal) to supportthe cooling body 211, an vibrating part 223 for imparting vibration frombelow, for example, to at least one of the pipes 222, and the coolingbody moving driving part (224) not shown that is moved, with oneterminal (right terminal) as the fulcrum, between the vibrating position(descending position) (the position shown in FIG. 8) at which thecooling body 211 is placed inside the mold 123 (descended position) (theposition shown in FIG. 8) and the non-vibrating position (ascendedposition) at which the cooling body 211 is placed outside the mold 131.

The cooling body cooling mechanism 231 comprises a flexible piping 232having one terminal connected to one of the pipes 222 and the otherterminal connected to the other pipe 222 and communicating with the flowpath formed inside the cooling body 211, a refrigerant storing part 233disposed halfway along the length of the piping 232, a refrigerantcooling part 234 disposed halfway along the length of the piping 232 andadapted to cool the refrigerant, and a pump 235 disposed halfway alongthe length of the piping 232 and adapted to circulate the refrigerant.

Now, the production of the ingot N will be described below. Since it isnearly wholly identical with that of the second embodiment, only theportions different from those of the second embodiment will bedescribed.

In the second embodiment illustrated in FIG. 4 and FIG. 5, when the mold131 is conveyed and stopped at the molten metal supplying position(vibrating position) (Pa), the cooling body moving driving part (224)not shown is actuated to insert the cooling body 211 into the mold 131,position it at the cooling body moving position (descended position) andset the vibrating part 223 into motion.

Then, by driving and descending the heater-embedded control bar (122)with the control bar driving part (123), the molten metal M is enabledto be delivered in a prescribed amount from the delivery tube (113) intothe mold 131.

The molten metal M which has been delivered in the prescribed amountinto the main body of the mold (132) as described above is poured ontothe cooling body 211 and cooled by contacting the surface of the coolingbody 211 kept cooled with the cooling body cooling mechanism 231 andconsequently crystallized and spheroidized and caused to adhere to thesurface of the cooling body 211.

Since the cooling body 211 is vibrated with the cooling body vibratingmechanism 221, the spherical crystals while in the process of growingare forcibly liberated from the surface of the cooling body 211 anddropped into the main body 132 of the mold.

Then, the molten metal M which has fallen into the main body 132 of themold is cooled by contacting the inner surface of the main body 132 ofthe mold and consequently grown into spherical crystals and allowed toadhere to the inner surface of the main body 132 of the mold.

After the mold 131 placed at the molten metal supplying position(vibrating position) (Pa) has been vibrated for a prescribed durationsuch as, for example, approximately in the range of one minute to fiveminutes as described above, the vibrating part 223 is stopped and thecooling body moving driving part (224) not shown is actuated to placethe cooling body 211 at the non-vibrating position (ascended position).

The subsequent steps are similar to those of the second embodiment.

According to the ingot producing device P of the third embodiment ofthis invention, since the cooling body 211 itself is capable of coolingthe molten metal M and the cooling body 211 is provided thereon with thecooling body vibrating mechanism 221 for the purpose of preventing themolten metal M from being solidified on the cooling body 211 andforcibly liberating and flowing down the crystals formed on the surfaceof the cooling body during the initial state of formation thereof, theingot N of the solid phase comprising fine spherical crystals can beefficiently produced without enlarging the device in use as comparedwith the conventional device of mechanical stirring or electromagneticstirring and without increasing the cost of energy.

Owing to the provision of the cooling body cooling mechanism 231 for thepurpose of cooling the cooling body 211, the cooling body 211 can beretained at a constant temperature and the ingot N of the solid phasecomprising fine spherical crystals can be produced efficiently.

FIG. 9 is an explanatory diagram equivalent to a lateral cross sectionschematically illustrating another example of the melting furnace to beused in the continuous cast bar producing device or the ingot producingdevice.

Referring to FIG. 9, the melting furnace 11, 111 comprises a main body12, 112 of the melting furnace opened in the upper part, a crucible 12A,112A removably contained as an internal vessel in the main body 12, 112of the melting furnace, a delivery tube 13, 113 mounted with watertightness as transfixed through the bottom of the main body 12, 112 ofthe melting furnace and enabled to transfix removably the bottom of themain body 12, 112 of the melting furnace and allow the upper terminalthereof to reach the prescribed position in the crucible 12A, 112A, aheater 14, 114 embedded in the main body 12, 112 of the melting furnace,and a lid 15, 115 for blocking the upper part of the main body 12, 112of the melting furnace.

Then, the melting furnace temperature adjusting mechanism 17, 117comprises a thermocouple 18, 118 as a temperature measuring device formeasuring the temperature in the melting furnace 11, 111 and anelectrification controlling part 19, 119 for starting supply of electricpower to the heater 14, 114 for enabling the temperature detected by thethermocouple 18, 118 to reach the prescribed melting temperature andstopping the supply of the electric power to the heater 14, 114.

Incidentally, the temperature of the interior of the melting furnace 11,111 is set by the melting furnace temperature adjusting mechanism 17,117 at a level not lower than the liquidus temperature of the magnesiumalloy so as to produce the molten metal M of a magnesium alloy.

The molten metal delivery controlling mechanism 21, 121 comprises aheater-embedded control bar 22, 122 inserted through the insertion hole15 a, 115 a formed in the lid 15, 115 of the melting furnace 11, 111 andcontrol bar driving part 23, 123 for inserting the heater-embeddedcontrol bar 22, 22 into the melting furnace 11, 11 and consequentlyexpelling the molten metal M through the delivery tube 13, 113.

Now, the melting furnace 11, 111 will be described below.

The melting furnace 11, 111 is not provided with a dross vent. When theyretain only small amounts of molten metal M and dross after they havedelivered the prescribed amounts of the molten metal M, the lid isopened to remove the crucible 12A, 112A from the interior of the mainbody 12, 112 of the melting furnace and a new crucible 12A, 112A iscontained in the main body7 12, 112 of the melting furnace asillustrated in FIG. 9.

Then, by charging the crucible 12A, 112A with necessary metals, closingthe main body 12, 112 of the melting furnace with the lid 15, 115, andheating the main body 112 of the melting furnace with the heater 114,thereby melting the metals, the molten metal M of a magnesium alloy canbe formed.

Thereafter, the molten metal M is successively delivered in theprescribed amount by manipulating the molten metal delivery controllingmechanism 21 and 121 in the same manner as already described.

The melting furnace 11, 111 is provided with a crucible 12A, 112A inplace of a dross vent. By replacing the crucible 12A, 112A, therefore,they are enabled to produce the molten metal M anew faster than theprocedure of newly forming the molten metal M by discharging the drossvia the dross vent.

As a result, the melting furnace is capable of producing the metalslurry U or the ingot N more efficiently.

When the crucible 12A, 112A removed from the interior of the main bodyof the melting furnace 12, 112 is made to contain cold water therein,the dross can be set by aging and removed.

The crucible 12A, 112A which has the dross set and removed as describedabove, therefore, can be prepared for the next service by having theinner peripheral surface thereof cleaned.

In the preceding embodiment, the molten metal M of the magnesium alloyto be handled is liable to undergo oxidation, it is preferred to behandled in an incombustible atmosphere such as, for example, the argongas or the mixture of sulfur hexafluoride (SF₆) gas with carbon dioxidegas.

While the molten metal M has been described by citing the case offorming the molten metal of a magnesium alloy, it goes without sayingthat this invention can be applied to aluminum alloys and other metals.

While the first embodiment has been described by citing the case ofmanufacturing a continuous cast bar B and billets L, this invention canbe applied to the production of a plate using the metal slurry U.

By providing the first embodiment with the cooling body 211 and thecooling body vibrating mechanism 221 (and further the cooling bodycooling mechanism 231) of the third embodiment in the place of thetilted cooling body 31 and the tilted cooling body vibrating mechanism36 or providing the cooling body 211 and the cooling body vibratingmechanism 221 (and further the cooling body cooling mechanism 231) ofthe third embodiment and causing the molten metal M from the tiltedcooling body 31 to pour into the cooling body 211, it is made possibleto obtain the same effect as in the first embodiment or the thirdembodiment.

In this case, the cooling body vibrating mechanism 221 does not need tobe moved as in the third embodiment.

While the second embodiment and the third embodiment have been describedby citing the case of producing a cylindrical ingot N, the casting(ingot) can be directly produced by performing the casting as aimed atproducing a casting.

By providing the second embodiment with the cooling body 211 and thecooling body vibrating mechanism 221 (and further the cooling bodycooling mechanism 231) of the third embodiment and causing the moltenmetal M from the cooling body 211 into the mold 131, it is made possibleto obtain the same effect as in the third embodiment.

The third embodiment has the effect thereof unimpaired by omitting thecooling body cooling mechanism 211.

INDUSTRIAL APPLICABILITY

The production of the metal slurry contemplated by this inventioncomprises pouring the molten metal into the tilted cooling body andcooling this molten metal on the tilted cooling body and meanwhileimparting vibration to the tilted cooling body, thereby forciblyliberating and flowing down the crystals being formed in the course ofcooling. Thus, it enables the metal slurry possessing fine sphericalcrystals to be efficiently and continuously produced.

It is, therefore, capable of producing the metal slurry easily even froman Mg alloy which has a small solidifying latent heat and is liable tosolidify. Owing to the impartation of the vibration in this case, thetime required for the spherical crystals to be liberated from thecooling body can be shortened and the produced crystal grains enjoyenhanced fineness.

Further, since the mold used for producing the ingot contemplated bythis invention is provided with the cooling body vibrating mechanism,the produced metal is enabled to acquire a minute spherical structureexcelling in mechanical properties.

1. A method for the production of metal slurry (U), comprising pouring amolten metal (M) onto a tilted cooling body (31) and allowing the moltenmetal to cool on the tilted cooling body, wherein vibration is impartedto the tilted cooling body.
 2. A method for the production of metalslurry (U), comprising pouring a molten metal (M) onto a vibratingcooling body (31) and causing the cooling body to cool the molten metal.3. A method according to claim 1 or claim 2, wherein the molten metal isformed of a magnesium alloy.
 4. A device for the production of metalslurry (U), comprising a tilted cooling body (31) onto which a moltenmetal (M) is poured to cool the molten metal and which is equipped witha tilted cooling body vibrating mechanism (36) for imparting vibrationto the tilted cooling body.
 5. A device for the production of metalslurry, comprising a cooling body (31) onto which a molten metal (M) ispoured and a cooling body vibrating mechanism (36) for impartingvibration to the cooling body.
 6. A device according to claim 4 or claim5, wherein the molten metal is formed of a magnesium alloy.
 7. A methodfor the production of an ingot (B, N), comprising supplying a mold (41)with a molten metal (M) and cooling the molten metal (M) by cooling themold, wherein vibration is imparted to the mold.
 8. A method for theproduction of an ingot (N), comprising pouring a molten metal (M) onto avibrating cooling body to cool the molten metal with the vibratingcooling body, supplying the cooled molten metal to a mold (41) andfurther cooling the cooled molten metal by cooling the mold.
 9. A methodaccording to claim 7 or claim 8, wherein the molten metal is formed of amagnesium alloy.
 10. A device for the production of an ingot (B, N),comprising a mold (131) to which a molten metal (U) is supplied andwhich is cooled and equipped with a mold vibrating mechanism (171) forimparting vibration to the mold (131).
 11. A device for the productionof an ingot (B, N), comprising a cooling body (211) onto which a moltenmetal (U) is poured for cooling the molten metal, a mold (131) to whichthe cooled molten metal is supplied and which is cooled to further coolthe cooled molten metal and a cooling body vibrating mechanism (221) forimparting vibration to the cooling body.
 12. A device according to claim10 or claim 11, wherein the molten metal is formed of a magnesium alloy.